前言

Feign组件默认使用Ribbon的重试机制并增加了根据状态码判断重试机制，默认情况下是不启用的。Feign使用的是Spring Retry组件，需要引入依赖才能启用。

一、POM引入Spring Retry

             
      
       org.springframework.retry
              
      
       spring-retry
        
     

 

二、配置文件

eureka-client:   ribbon:      MaxAutoRetries: 1      MaxAutoRetriesNextServer: 1      retryableStatusCodes: 500,404       OkToRetryOnAllOperations: true       NFLoadBalancerRuleClassName: com.netflix.loadbalancer.AvailabilityFilteringRule #负载均衡规则

 

eureka-client是自己的serverId，MaxAutoRetries同一台服务器上的最大重试次数（不包括第一次尝试），MaxAutoRetriesNextServer要重试的下一个服务器的最大数量（不包括第一个服务器），retryableStatusCodes可以根据接口返回的状态码判断是否重试其他服务，OkToRetryOnAllOperations只对所有的超时请求重试

注意： Ribbon的重试机制只有对GET请求或者设置了OkToRetryOnAllOperations生效 详情请查看源码：

public class RibbonLoadBalancedRetryPolicy implements LoadBalancedRetryPolicy {    ...        public Boolean canRetry(LoadBalancedRetryContext context) {        HttpMethod method = context.getRequest().getMethod();        return HttpMethod.GET == method || lbContext.isOkToRetryOnAllOperations();    }    ...}

 

Feign对返回状态码做了重试判断RetryableFeignLoadBalancer

public class RetryableFeignLoadBalancer extends FeignLoadBalancer    implements ServiceInstanceChooser {    ...        [@Override](https://my.oschina.net/u/1162528)    public RibbonResponse execute(final RibbonRequest request,                IClientConfig configOverride) throws IOException {        ...                if (retryPolicy != null                                && retryPolicy.retryableStatusCode(response.status())) {            byte[] byteArray = response.body() == null ? new byte[] {}                                        : StreamUtils                                                .copyToByteArray(response.body().asInputStream());            response.close();            throw new RibbonResponseStatusCodeException(                                        RetryableFeignLoadBalancer.this.clientName, response,                                        byteArray, request.getUri());        }        ...    }    ...}

 

重试机制用的是Spring Retry组件当抛出异常时进行重试！

GET请求指的是feign client 请求其他client时声明的那个interface中mapping注解类型，RequestMapping不设置method默认为GET请求

@FeignClient("stores")public interface StoreClient {    @RequestMapping(method = RequestMethod.GET, value = "/stores")        List
     
       getStores();    @RequestMapping(method = RequestMethod.POST, value = "/stores/{storeId}", consumes = "application/json")        Store update(@PathVariable("storeId") long storeId, Store store);}
     

 

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